hi carpethead, and welcome to the forum.
finding content can be tricky if you're looking for specific authors who aren't available in ebooks (sadly, this is still true for quite a lot of them). some people go so far as to scan their paper books and make their own ebooks to get around this problem.
the good news is, i think science fiction and fantasy are perhaps the best represented genres currently in ebooks. if you're open to discovering new authors you should find plenty to read.
i recommend you start at baen books : they have a
free library where you can try out their authors, and they sell their books for really reasonable prices and with no drm via their
webscriptions site (take a look at the monthly bundles ; i think someone said they bring the price per book down to something like 3$).
also take a look at fictionwise.com and booksonboard.com.
there is also more free stuff available than you could possibly read in your lifetime from a variety of sources, starting right here : take a look at our free ebooks (click on the ebooks link in the blue navigation bar at the top of the page) made by our members. another excellent place is feedbooks.com ; free public domain and creative commons works including by contemporary authors (and some of our own members ! like
PJ Lyon, better known as moejoe around here). and as already mentioned, our wiki lists a lot of great places to find books.
and take a look in the reading recommendations forum for more advice about authors to try. you can look at the ongoing science fiction recommendations threads or start your own ; list a few authors you like and see what people come up with. a lot of members here love science fiction and can give you plenty of titles and authors to try out.
more and more authors are making their works available digitally but admittedly it's still a slow process, but i think once you find a few good sites you'll find plenty to interest you. and you'll soon find ebooks quite addictive, for many reasons.
